This invention relates to plate filter presses and more particularly is concerned with apparatus suitable for shifting the plates of a plate filter press.
Plate filter presses comprise a plurality of filter plates slidably carried by a suitable carrier member; for instance, the filter plates may be either slidably mounted on a carriageway arranged alongside the filter press or slidably suspended from a carrier member arranged above the filter press.
Filter presses generally comprise a battery of up to 100 or more filter plates.
In one well known type of plate filter press, each filter plate is recessed on its faces, and each adjacent pair of filter plates defines a filter-pressing cavity. This type of plate filter press is generally known as the `recessed plate` type.
In another well known type of plate filter press, a plurality of filter plates alternate with a plurality of frames; the frames define the edges of the filter-pressing cavities while the plates, when in position, define the sides of the cavities. This type of plate filter press is generally known as the `plate and frame` type or as the `flush-plate` type.
In order to effect filtering, the plates are compressed, generally by a horizontally-mounted, hydraulic ram, with the plates contacting each other or their associated frames in a sealable manner, and with the material to be filtered present in slurry form in each filter-pressing cavity. When the filtering operation is complete, the hydraulic ram pressure is released, after which it is necessary to separate the plates or plates and frames and to dislodge the filtered material from each filter-pressing cavity; the dislodged filter material conveniently falls onto a conveyor belt mounted under the filter press.
Further details regarding the construction and operation of plate filter presses can be found, for example, in Chapter 19 of the 5th Edition of the Chemical Engineer's Handbook by Robert H. Perry and Cecil H. Chilton published in 1973 by McGraw-Hill Inc.
The separation of the filter plates, each of which can weigh up to 100 lbs or more, may be performed either manually, for example by two men, one on each side of the press, each using a crowbar to lever the plates apart, or automatically by complicated and expensive equipment which is an integral part of the ancillary equipment of each filter press and which is generally hydraulically or pneumatically operated. A disadvantage of this type of automatic equipment is that, although the plate separation operation is performed by a machine, operators are still necessary to assist in the manual dislodging of the filtered material from each cavity; and it will be appreciated that, once an automatic plate separation sequence is initiated, any delay in dislodging the filtered material from the cavity puty the operator(s) at risk in view of the possibility of an arm or hand being trapped by the next plate in the sequence as it is automatically moved along. Sophisticated photocell-initiated safeguard systems are known for obviating or reducing this risk to the operator, but such systems inevitably increase the cost of the equipment.
It is therefore an object of the present invention to provide a plate-separation device which is power-drivable but is manually-operable.